<head>
	<meta charset="UTF-8">
	<title></title>
	<style>
		* {
			margin: 0 auto;
			padding: 0;
		}
		
		body {
			width: 200px;
		}
	</style>
</head>

<body><canvas id="myCan" width="500" height="500" style="border:1px solid #d3d3d3;"></canvas>
	<script>
		var can = document.getElementById("myCan");
		var cans = can.getContext('2d');
		cans.arc(250, 250, 240, 0, 2 * Math.PI);
		cans.stroke();
	</script>
</body>

</html>